Print Head Ejection Direction Control for Inkjet Color Consistency
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Solution Overview
Problem
Existing inkjet printers face issues in maintaining color consistency when printing the same color in different directions due to variations in ink overlapping order, leading to recognizable color differences, especially at the boundaries of band regions.
Innovation Solution
An image processing apparatus that determines the ejection direction of the print head for each band image based on color gap information, using adjacent-state and separate-state color gap data to adjust the ink overlapping order and minimize color differences perceived by observers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If bidirectional printing is used to improve printing speed, then productivity increases, but color consistency deteriorates due to different ink overlapping orders in different directions
Solution Approach 1:
The patent applies local quality by differentiating the treatment of band regions based on their position. Boundary blocks (adjacent to other band regions) use a lower threshold for direction determination, while internal blocks (separated from boundaries) use a higher threshold. This localized approach allows the system to maintain color consistency at critical boundary areas while permitting bidirectional printing in internal areas to maximize printing speed.
Solution Approach 2:
The patent implements dynamics by making the print head movement direction adaptive rather than fixed. The control unit dynamically determines the ejection execution direction for each band image based on real-time evaluation of color gap information and adjacent/separated state. This dynamic direction selection ensures that printing direction changes only when necessary to maintain color consistency, otherwise bidirectional printing continues to improve speed.
2Device complexity
If a single threshold value is used for direction determination, then device complexity is reduced, but manufacturing precision deteriorates because it cannot account for different recognizability at boundary and internal blocks
Solution Approach 1:
The patent applies segmentation by dividing the band region into two distinct types of blocks: boundary blocks (adjacent to other band regions) and internal blocks (separated from boundaries). Each block type is assigned a different threshold value for direction determination. This segmentation allows the system to use simpler single-value thresholds for each category while achieving the precision of multi-value thresholds, thus resolving the contradiction between device complexity and manufacturing precision.
Data Source
AI summary
An image processing apparatus includes a controller for controlling a print execution unit. The print execution unit repeatedly performs ejection processing of ejecting a droplet of color material onto a printing medium. The controller is configured to perform: specifying an estimate value for a target partial image by using color gap information, the target partial image being selected among a plurality of partial images included in an N-th band image; determining whether the estimate value satisfies an estimate condition; determining an ejection execution direction with respect to an N-th ejection processing to be a first direction in response to determination that the estimate value satisfies the estimate condition; and determining the ejection execution direction with respect to the N-th ejection processing to be opposite to the ejection execution direction with respect to an (N−1)-th ejection processing in response to determination that the estimate value does not satisfy the estimate condition.